<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 
<html>
<head>
<title>Menus &amp; toolbars in QtJambi</title>
<link rel="stylesheet" href="/cfg/format.css" type="text/css">
<meta http-equiv="content-type" content="text/html; charset=utf-8">
<meta name="keywords" content="GUI, menu, toolbar, QtJambi, Java">
<meta name="description" content="Menus &amp; toolbars in QtJambi">
<meta name="language" content="en">
<meta name="author" content="Jan Bodnar">
<meta name="distribution" content="global">

<script type="text/javascript" src="/lib/jquery.js"></script>
<script type="text/javascript" src="/lib/common.js"></script>

</head>

<body>

<div class="container">

<div id="wide_ad" class="ltow">
<script type="text/javascript"><!--
google_ad_client = "pub-9706709751191532";
/* 160x600, August 2011 */
google_ad_slot = "2484182563";
google_ad_width = 160;
google_ad_height = 600;
//-->
</script>
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script>
</div>

<div class="content">

<a href="/" title="Home">Home</a>&nbsp;
<a href="..">Contents</a>


<h1>Menus &amp; toolbars in QtJambi</h1>

<p>
In this part of the QtJambi programming tutorial, we will work with menus and toolbar. 
</p>

<div class="center"> 
<script type="text/javascript"><!--
google_ad_client = "pub-9706709751191532";
/* horizontal */
google_ad_slot = "1734478269";
google_ad_width = 468;
google_ad_height = 60;
//-->
</script> 
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js"> 
</script> 
</div> 

<p>
A menubar is one of the most visible parts of the GUI application. 
It is a group of commands located in various menus. While in console 
applications you had to remember all those arcane commands, here we have 
most of the commands grouped into logical parts. There are accepted standards
that further reduce the amount of time spending to learn a new application.
Menus group commands that we can use in an application. 
Toolbars provide a quick access to the most frequently used commands.
</p>


<h>Simple menu</h2>

<p>
The first example will show a simple menu. 
</p>

<pre class="code">
package com.zetcode;

import com.trolltech.qt.gui.QAction;
import com.trolltech.qt.gui.QApplication;
import com.trolltech.qt.gui.QMainWindow;
import com.trolltech.qt.gui.QMenu;

/**
 * ZetCode QtJambi tutorial
 *
 * This program shows a simple
 * menu. It has one action, which
 * will terminate the program, when
 * selected. 
 *
 * @author jan bodnar
 * website zetcode.com
 * last modified March 2009
 */

public class JambiApp extends QMainWindow {
    
    public JambiApp() {

        setWindowTitle("Simple menu");

        initUI();
        
        resize(250, 200);
        move(300, 300);
        show();
    }

    private void initUI() {

        QAction quit = new QAction("&amp;Quit", this);

        QMenu file = menuBar().addMenu("&amp;File");
        file.addAction(quit);

        quit.triggered.connect(QApplication.instance(), "quit()");
    }
    
    
    public static void main(String[] args) {
        QApplication.initialize(args);
        new JambiApp();
        QApplication.exec();
    }
}
</pre>

<p>
We have a menubar, a menu and an action. In order to work with menus,
we must inherit from <b class="keyword">QMainWindow</b> widget. 
</p>

<pre class="explanation">
QAction quit = new QAction("&amp;Quit", this);
</pre>

<p>
This code line creates a <b class="keyword">QAction</b>. Each <b class="keyword">QMenu</b> has one or more action objects.
Note the ampersand (&amp;) character. It creates a shortcut for the item. Alt + Q. It also underlines the Q character. 
The shortcut is active, when the file menu is dropped down. 
</p>

<pre class="explanation">
QMenu file = menuBar().addMenu("&amp;File");
file.addAction(quit);
</pre>

<p>
We create a <b class="keyword">QMenu</b> object. The ampersand character creates a shortcut. Alt + F. 
The consecutive shortcuts Alt + F, Alt + Q quit the application. 
</p>

<pre class="explanation">
quit.triggered.connect(QApplication.instance(), "quit()");
</pre>

<p>
When we select this option from the menu, the application quits. 
</p>

<br>
<img src="/img/gui/qtjambi/simplemenu.png" alt="Simple menu">
<div class="figure">Figure: Simple menu</div>

<h2>Creating a submenu</h2>

<p>
A submenu is a menu plugged into another menu object. The next example demonstrates this. 
</p>

<pre class="code">

package com.zetcode;

import com.trolltech.qt.gui.QAction;
import com.trolltech.qt.gui.QApplication;
import com.trolltech.qt.gui.QMainWindow;
import com.trolltech.qt.gui.QMenu;

/**
 * ZetCode QtJambi tutorial
 *
 * This program creates a
 * submenu
 *
 * @author jan bodnar
 * website zetcode.com
 * last modified March 2009
 */

public class JambiApp extends QMainWindow {
    
    public JambiApp() {

        setWindowTitle("Submenu");

        initUI();

        resize(250, 200);
        move(300, 300);
        show();
    }

    private void initUI() {

        QAction quit = new QAction("&amp;Quit", this);

        QMenu file = menuBar().addMenu("&amp;File");
        QMenu impm = new QMenu("Import");

        QAction seeds = new QAction("Import news feed...", this);
        QAction marks = new QAction("Import bookmarks...", this);
        QAction mail = new QAction("Import mail...", this);
        impm.addAction(seeds);
        impm.addAction(marks);
        impm.addAction(mail);

        file.addMenu(impm);
        file.addAction(quit);

        quit.triggered.connect(QApplication.instance(), "quit()");
    }
    
        
    public static void main(String[] args) {
        QApplication.initialize(args);
        new JambiApp();
        QApplication.exec();
    }
}
</pre>

<p>
In the example, we have three options in a submenu of a file menu. 
</p>

<pre class="explanation">
QMenu file = menuBar().addMenu("&amp;File");
QMenu impm = new QMenu("Import");
</pre>

<p>
We have two <b class="keyword">QMenu</b> objects. The file menu and the import menu. 
</p>

<pre class="explanation">
QAction seeds = new QAction("Import news feed...", this);
QAction marks = new QAction("Import bookmarks...", this);
QAction mail = new QAction("Import mail...", this);
</pre>

<p>
We create three action objects.  
</p>

<pre class="explanation">
impm.addAction(seeds);
impm.addAction(marks);
impm.addAction(mail);
</pre>

<p>
We add the action objects into the import menu. 
</p>

<pre class="explanation">
file.addMenu(impm);
</pre>

<p>
Finally, we add the import menu into the file menu. 
</p>

<br>
<img src="/img/gui/qtjambi/submenu.png" alt="Submenu">
<div class="figure">Figure: Submenu</div>


<h2>Images, menus, separators</h2>

<p>
In the following example, we will further enhance our previous application. 
We will add icons to the menus, use shortcuts and a separator. 
</p>

<pre class="code">
package com.zetcode;

import com.trolltech.qt.gui.QAction;
import com.trolltech.qt.gui.QApplication;
import com.trolltech.qt.gui.QIcon;
import com.trolltech.qt.gui.QMainWindow;
import com.trolltech.qt.gui.QMenu;

/**
 * ZetCode QtJambi tutorial
 *
 * This program shows image
 * menus, shortcuts and a separator
 *
 * @author jan bodnar
 * website zetcode.com
 * last modified March 2009
 */

public class JambiApp extends QMainWindow {
    
    public JambiApp() {

        setWindowTitle("Image menu");

        initUI();

        resize(250, 200);
        move(300, 300);
        show();
    }

    private void initUI() {

          QIcon newpix = new QIcon("new.png");
          QIcon openpix = new QIcon("open.png");
          QIcon quitpix = new QIcon("quit.png");

          QAction newa = new QAction(newpix, "&amp;New", this);
          QAction open = new QAction(openpix, "&amp;Open", this);
          QAction quit = new QAction(quitpix, "&amp;Quit", this);
          quit.setShortcut("Ctrl+Q");

          QMenu file;
          file = menuBar().addMenu("&amp;File");
          file.addAction(newa);
          file.addAction(open);
          file.addSeparator();
          file.addAction(quit);

          quit.triggered.connect(QApplication.instance(), "quit()");
    }
    
    
    public static void main(String[] args) {
        QApplication.initialize(args);
        new JambiApp();
        QApplication.exec();
    }
}

</pre>

<p>
In our example, we have one menu with three actions. Only the quit action will 
actually do something, if we select it. We also create a separator and a Ctrl + Q shortcut,
which will terminate the application. 
</p>

<pre class="explanation">
QIcon newpix = new QIcon("new.png");
QIcon openpix = new QIcon("open.png");
QIcon quitpix = new QIcon("quit.png");
</pre>

<p>
These are png images, that we will use in the application. 
</p>

<pre class="explanation">
QAction newa = new QAction(newpix, "&amp;New", this);
QAction open = new QAction(openpix, "&amp;Open", this);
QAction quit = new QAction(quitpix, "&amp;Quit", this);
</pre>

<p>
Here we create three action objects. The first parameter is the <b class="keyword">QIcon</b>.
</p>

<pre class="explanation">
quit.setShortcut("Ctrl+Q");
</pre>

<p>
This line creates a shortcut. By pressing this shortcut, we will run the quit action, 
which will quit the application. 
</p>

<pre class="explanation">
file.addSeparator();
</pre>

<p>
We create a separator. The separator is a horizontal line, which enables us to group menu actions 
into some logical parts. 
</p>


<br>
<img src="/img/gui/qtjambi/imshsep.png" alt="Images, shortcut and a separator">
<div class="figure">Figure: Images, shortcut and a separator</div>



<h2>A toolbar</h2>

<p>
The <b class="keyword">QToolBar</b> class provides a movable panel that contains a
 set of controls, which provide a quick access to the application actions. 
</p>

<pre class="code">
package com.zetcode;

import com.trolltech.qt.gui.QAction;
import com.trolltech.qt.gui.QApplication;
import com.trolltech.qt.gui.QIcon;
import com.trolltech.qt.gui.QMainWindow;
import com.trolltech.qt.gui.QToolBar;

/**
 * ZetCode QtJambi tutorial
 *
 * This program creates a 
 * toolbar
 *
 * @author jan bodnar
 * website zetcode.com
 * last modified April 2009
 */

public class JambiApp extends QMainWindow {
    
    public JambiApp() {

        setWindowTitle("Toolbar");
        
        initUI();

        resize(250, 200);
        move(300, 300);
        show();
    }

    private void initUI() {

        QIcon newpi = new QIcon("new.png");
        QIcon openpi = new QIcon("open.png");
        QIcon quitpi = new QIcon("quit.png");

        QToolBar toolbar = addToolBar("main toolbar");
        toolbar.addAction(newpi, "New File");
        toolbar.addAction(openpi, "Open File");
        toolbar.addSeparator();
        QAction quit = toolbar.addAction(quitpi,
            "Quit Application");

        quit.triggered.connect(QApplication.instance(), "quit()");

    }
   
    
    public static void main(String[] args) {
        QApplication.initialize(args);
        new JambiApp();
        QApplication.exec();
    }
}
</pre>

<p>
We create a toolbar with three action objects and one separator. 
</p>

<pre class="explanation">
QIcon newpi = new QIcon("new.png");
QIcon openpi = new QIcon("open.png");
QIcon quitpi = new QIcon("quit.png");
</pre>

<p>
Toolbar action objects will display these icons.
</p>

<pre class="explanation">
QToolBar toolbar = addToolBar("main toolbar");
</pre>

<p>
The <b class="keyword">addToolBar()</b> method of the <b class="keyword">QMainWindow</b>
creates a toolbar for the application. The text string gives a toolbar a name. This name
is used to reference this toolbar, because there can be multiple toolbars in one application.
If we right click on the window area, we can see a checkable option, which shows/hides the
toolbar. 
</p>

<pre class="explanation">
toolbar.addSeparator();
</pre>

<p>
We create a vertical separator.
</p>

<pre class="explanation">
quit.triggered.connect(QApplication.instance(), "quit()");
</pre>

<p>
When we click on the quit action object, the application terminates. 
</p>

<br>
<img src="/img/gui/qtjambi/toolbar.png" alt="Toolbar">
<div class="figure">Figure: Toolbar</div>


<h2 id="undoredo">Undo redo</h2>

<p>
The following example demonstrates, how we can deactivate toolbar buttons 
on the toolbar. It is a common practice in GUI programming. For example 
the save button. If we save all changes of our document to the disk,
the save button is deactivated in most text editors. This way the 
application indicates to the user, that all changes are already saved. 
</p>

<pre class="code">

package com.zetcode;

import com.trolltech.qt.QSignalEmitter;
import com.trolltech.qt.gui.QAction;
import com.trolltech.qt.gui.QApplication;
import com.trolltech.qt.gui.QIcon;
import com.trolltech.qt.gui.QMainWindow;
import com.trolltech.qt.gui.QToolBar;

/**
 * ZetCode QtJambi tutorial
 *
 * This program disables/enables
 * actions on a toolbar
 *
 * @author jan bodnar
 * website zetcode.com
 * last modified March 2009
 */

public class JambiApp extends QMainWindow {

    private int count = 0;
    private QAction undo;
    private QAction redo;

    public JambiApp() {

        setWindowTitle("Undo redo");

        initUI();

        resize(300, 200);
        move(400, 300);
        show();
    }

    private void initUI() {

        QIcon undoi = new QIcon("undo.png");
        QIcon redoi = new QIcon("redo.png");
        QIcon quitpi = new QIcon("quit.png");

        QToolBar toolbar = addToolBar("first toolbar");

        undo = toolbar.addAction(undoi, "Undo");
        redo = toolbar.addAction(redoi, "Redo");

        undo.triggered.connect(this, "count()");
        redo.triggered.connect(this, "count()");

        toolbar.addSeparator();

        QAction quit = toolbar.addAction(quitpi, "Quit Application");
        quit.triggered.connect(QApplication.instance(), "quit()");

    }


    private void count() {
        
        QAction action = (QAction) QSignalEmitter.signalSender();

        if ("Undo".equals(action.text())) {
            count += -1;
        } else {
            count += 1;
        }

        if (count <= 0) {
            undo.setDisabled(true);
            redo.setDisabled(false);
        }

        if (count >= 5) {
            undo.setDisabled(false);
            redo.setDisabled(true);
        }
    }
    
    
    public static void main(String[] args) {
        QApplication.initialize(args);
        new JambiApp();
        QApplication.exec();
    }
}
</pre>

<p>
In our example, we have three <b class="keyword">QAction</b> objects and a separator.
After several clicks on the undo or redo buttons, they become deactivated. 
Visually, the buttons are grayed out. 
</p>

<pre class="explanation">
private int count = 0;
</pre>

<p>
The count variable determines, which button is activated and deactivated. 
</p>

<pre class="explanation">
undo.triggered.connect(this, "count()");
redo.triggered.connect(this, "count()");
</pre>

<p>
Clicking on the toolbar button, the <b class="keyword">triggered</b> signal is emitted.
We connect this signal to the <b class="keyword">count()</b> method.
</p>

<pre class="explanation">
QAction action = (QAction) QSignalEmitter.signalSender();
</pre>

<p>
Both toolbar buttons call the <b class="keyword">count()</b> method. We need to tell
between them. This line determines, which action object actually emitted the signal. 
</p>

<pre class="explanation">
if ("Undo".equals(action.text())) {
    count += -1;
} else {
    count += 1;
}
</pre>

<p>
The undo toolbar button subtracts 1 from the count variable. The 
redo adds 1. Depending on the value of the count variable, we enable/disable
the toolbar buttons.
</p>

<pre class="explanation">
if (count <= 0) {
    undo.setDisabled(true);
    redo.setDisabled(false);
}
</pre>

<p>
The <b class="keyword">setDisabled()</b> method activates or deactivates the
toolbar buttons. 
</p>

<br>
<img src="/img/gui/qtjambi/undoredo.png" alt="Undo redo">
<div class="figure">Figure: Undo redo</div>

<hr class="btm">

<p>
In this part of the QtJambi tutorial, we mentioned the menus and toolbars. 
</p>

<br>
<div class="center"> 
<script type="text/javascript"><!--
google_ad_client = "pub-9706709751191532";
/* horizontal */
google_ad_slot = "1734478269";
google_ad_width = 468;
google_ad_height = 60;
//-->
</script> 
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js"> 
</script> 
</div> 
<br>

<div class="botNav, center">
<span class="botNavItem"><a href="/">Home</a></span> ‡ <span class="botNavItem"><a href="..">Contents</a></span> ‡
<span class="botNavItem"><a href="#">Top of Page</a></span>
</div>


<div class="footer">
<div class="signature">
<a href="/">ZetCode</a> last modified April 28, 2009  <span class="copyright">&copy; 2007 - 2012 Jan Bodnar</span>
</div>
</div>

</div> <!-- content -->

</div> <!-- container -->

</body>
</html>
